By purchasing this item you can directly exchange 30 for 3000 Nano Spores.
Beginning in Update 9 materials could be purchased directly from the market for Platinum.
Saturn, Neptune, Eris and Orokin Derelict Survivals and Defense missions are the best way to get nano spores quickly. Usually you can get 3,000 per 5 minutes or waves, doubled if you have Nekros with you. They are also great places to farm plastids for Saturn, Eris and Orokin Derelict and ferrite for Neptune.